Photoluminescent and electroluminescent properties of GaAs/sub 1-x/P/sub x/-GaAs/sub 1-y/P/sub y/ isotype heterojunction electrodes

The photoluminescence (PL) of N-n GaAs/sub 0.59/P/sub 0.41/-GaAs/sub 0.70/P/sub 0.30/ heterojunction electrodes has been studied in stable, efficient photoelectrochemical cells employing aqueous ditelluride electrolyte. When excited at several ultra-band-gap wavelengths, electrodes whose surface n-GaAs/sub 0.70/P/sub 0.30/ layers are approx.0.2 μm thick exhibit PL spectra derived from the emission bands of the heterojunction constituents. Besides being dependent on excitation wavelength, the PL spectral distribution is a function of applied potential. Field-induced quenching of PL from the electrodes is shown to be consistent with a dead-layer model. Electroluminescence (EL) can be observed when the solids are used as cathodes in a formamide solution of Na2S2O8. The EL spectrum indicates that radiative recombination due to hole injection is largely confined to the surface layer